Color lighting systems are found in a variety of entertainment facilities, to include theaters, auditoriums, concert halls and stadiums. Regardless the size of the venue, in almost all instances a color lighting system is required or desired. The quality of the entertainment provided is often dependent, in part, on the quality of the color lighting system.
Aside from professional and amateur entertainment venues, theme parks and other such attractions use color light to enhance the experience of their customers. Private and public facilities, such as churches and museums, also have a need for variable color lighting. Further, sales oriented facilities and events, to include shopping malls and trade shows, rely on color lighting to help market products. Also, there are many scientific/engineering applications where discriminating color light is important. It is simply a fact of life that color lighting is part of almost every person's daily routine.
Typically, color light systems include a broad band, white light source, the output of which must be filtered to produce the desired color(s) of light. Often, the broadband light is unpolarized, and a portion of the light is reflected (“thrown away”) in a first, polarizing step. The loss of 50% or more of the incoming light at the onset reduces the intensity of the generated light, as well as the variations in color that may be achieved.
In many instances, color filtering includes the use of “color wheels”. Generally speaking, color wheels rely on the movement (rotation or otherwise) of color filters into and out of optical alignment with a transmitted white light. In many instances, the color filters are dichroic filters, which is to say they filter (reflect or absorb) light within one wavelength band and pass through all remaining light. The filters may be glass, gelatin, or other transparent/semi-transparent materials. Often, the number of possible color combinations is limited by the number of color filters that can be mounted into the color wheel. Further, the clarity of colors is affected by filter movement, alignment, etc.
Absorption is the most prevalent means for filtering colored light. Unfortunately, absorbed light can generate significant quantities of heat which must be dissipated by the lighting system. Operational heating also limits the optical power of a system, as there is a direct correlation between optical power and absorbed heat. System cooling requirements typically require active (e.g. fans) or passive (e.g. cooling fins) cooling subsystems. In addition to heating concerns, standard color wheel systems include multiple moving, mechanical components. The process of changing colors is distracting to the audience. Also, moving parts impede or limit the response time/speed of a system, as well as reduce system reliability. In most instances, the useful operational life of a system is severely limited by reliability issues.
Pixilated color lighting systems are yet another lighting option found in the prior art. Unlike color wheel systems which are subtractive (filtering) in nature, pixilated systems are additive. Stated differently, pixilated systems achieve desired color combinations by adding colors together at a level unresolved by the naked human eye. Red, green and blue pixels produce an image on a screen, or alternatively direct color light to a designated region. Fiber optics or other delivery methods carry the colored light from light sources to the pixilated surface. Although operationally cooler, and void of multiple moving parts, pixilated systems are not without their limitations. A ⅔ decrease in light intensity results from the use of a broadband while light source and red, green and blue pixel elements. To obtain red, green and blue light from the broadband white light, the light must pass through a matrix of red, green and blue absorptive “dots”. On each dot or pixel, two of the three colors (i.e. green and blue on a red dot) are absorbed. Therefore, by converting the broadband white light to red, green, and blue, ⅔ of the light is lost in the conversion. This loss precedes any further losses associated with transmitting and mixing the light.
In addition to needing color light, venues such as theaters, theme parks and trade shows often desire to shape the color light to create various images. The methods used, e.g. gobos or reflective display devices, are often times separate from the color lighting system. Integration, therefore, of the color lighting system and the imaging generating device can be cumbersome and inefficient.
Hence, there is a need for a color filter device and color filter system that overcome one or more of the limitations discussed above.